Sponge skeletons as an important sink of silicon in the global oceans

Type Article
Date 2019-10
Language English
Author(s) Maldonado Manuel1, López-Acosta María1, Sitjà Cèlia1, García-Puig Marta1, Galobart Cristina1, Ercilla Gemma2, Leynaert Aude3
Affiliation(s) 1 : Center for Advanced Studies of Blanes (CEAB), Spanish National Research Council (CSIC), Girona, Spain
2 : Institute of Marine Sciences (ICM-CSIC), Barcelona, Spain
3 : University of Brest, CNRS, LEMAR, Plouzané, France
Source Nature Geoscience (1752-0894) (Springer Science and Business Media LLC), 2019-10 , Vol. 12 , N. 10 , P. 815-822
DOI 10.1038/s41561-019-0430-7
WOS© Times Cited 20
Abstract

Silicon (Si) is a pivotal element in the biogeochemical and ecological functioning of the ocean. The marine Si cycle is thought to be in internal equilibrium, but the recent discovery of Si entries through groundwater and glacial melting have increased the known Si inputs relative to the outputs in the global oceans. Known outputs are due to the burying of diatom skeletons or their conversion into authigenic clay by reverse weathering. Here we show that non-phototrophic organisms, such as sponges and radiolarians, also facilitate significant Si burial through their siliceous skeletons. Microscopic examination and digestion of sediments revealed that most burial occurs through sponge skeletons, which, being unusually resistant to dissolution, had passed unnoticed in the biogeochemical inventories of sediments. The preservation of sponge spicules in sediments was 45.2 ± 27.4%, but only 6.8 ± 10.1% for radiolarian testa and 8% for diatom frustules. Sponges lead to a global burial flux of 1.71 ± 1.61 TmolSi yr−1 and only 0.09 ± 0.05 TmolSi yr−1 occurs through radiolarians. Collectively, these two non-phototrophically produced silicas increase the Si output of the ocean to 12.8 TmolSi yr−1, which accounts for a previously ignored sink that is necessary to adequately assess the global balance of the marine Si cycle.

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Publisher's official version 9 3 MB Open access
Supplementary data tables 1–4, Supplementary figs 1–5, Supplementary dicussion, Supplementary methods and Supplementary references. 16 2 MB Open access
Supplementary Methods data (Table 1). 12 KB Open access
Supplementary Methods data (Table 2). 13 KB Open access
Supplementary data for burial depth and Si preservation. 15 KB Open access
Supplementary data for deposition rate and sponge and radiolarian burial rate. 13 KB Open access
Supplementary data for global ocean Si burial and preservation. 12 KB Open access
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